3 Rib Tractor Tires

tractor
A tractor is a vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction.
A powerful motor vehicle with large rear wheels, used chiefly on farms for hauling equipment and trailers
A short truck consisting of the driver's cab, designed to pull a large trailer
a truck that has a cab but no body; used for pulling large trailers or vans
a wheeled vehicle with large wheels; used in farming and other applications

tires
Become in need of rest or sleep; grow weary
Cause to feel in need of rest or sleep; weary
(tire) exhaust or get tired through overuse or great strain or stress; "We wore ourselves out on this hike"
(tire) lose interest or become bored with something or somebody; "I'm so tired of your mother and her complaints about my food"
(tire) hoop that covers a wheel; "automobile tires are usually made of rubber and filled with compressed air"
Lose interest in; become bored with

rib
Mark with or form into raised bands or ridges
Tease good-naturedly
any of the 12 pairs of curved arches of bone extending from the spine to or toward the sternum in humans (and similar bones in most vertebrates)
support resembling the rib of an animal
form vertical ribs by knitting; "A ribbed sweater"

3
A performance appraisal, employee appraisal, performance review, or (career) development discussion is a method by which the job performance of an employee is evaluated (generally in terms of quality, quantity, cost, and time) typically by the corresponding manager or supervisor .
three: the cardinal number that is the sum of one and one and one
three: being one more than two